AIDS is a disease which is caused due to human T-cells being infected with AIDS virus. AIDS has brought about problems in human society. Several agents for inactivating HIV are reported. However, any of these HIV-inactivating agents is not necessarily satisfactory as a remedial agent for AIDS. Accordingly, there exists an outstanding demand to develope and provide such a new antiviral agent which is of low toxicity but can show a high activity to inhibit the infection of human T-cells with HIV.
On the other hand, D-.beta.-lysylmethanediamine as obtained earlier by the present inventors is an antibiotic which has weak antibacterial activity against Gram-positive bacteria. D-.beta.-Lysylmethanediamine has the unique structure represented by the following formula (I) ##STR2## This compound is a known antibiotic which is produced by a microorganism, Streptomyces nashvillensis and which was reported by the present inventors (see "Journal of Antibiotics" Vol. 39, No. 3, page 476 (1986) and Japanese patent application first publication "Kokai" Sho-62-114947 specification published 26 May 1987). D-.beta.-Lysylmethanediamine hemi-carbonate (1/2 H.sub.2 CO.sub.3) is in the form of a colorless powder which is hygroscopic but has no definite melting point measurable. Its specific optical rotation is [.alpha.].sub.D.sup.26 -7.4.degree. (c 0.5, water).
An object of this invention is to provide a new antiviral agent which inhibits strongly the infection of human T-cells with HIV but exhibits a low toxicity to mammals and which is expectable to be useful as a remedial agent for AIDS. Another object of this invention is to provide a new pharmaceutical composition which inhibits the infection with AIDS virus. Further object of this invention is to provide a therapeutic method for inhibiting the infection of human T-cells with HIV. Further another objects of this invention will be clear from the following descriptions.